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color.go
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color.go
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/*
* FrankyGo - UCI chess engine in GO for learning purposes
*
* MIT License
*
* Copyright (c) 2018-2020 Frank Kopp
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in all
* copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
* SOFTWARE.
*/
package types
import "fmt"
// Color represents constants for each chess color White and Black
type Color uint8
// Constants for each color
const (
White Color = 0
Black Color = 1
ColorLength int = 2
)
// Flip returns the opposite color
func (c Color) Flip() Color {
return c ^ 1
}
// IsValid checks if f represents a valid color
func (c Color) IsValid() bool {
return c < 2
}
// String returns a string representation of color as "w" or "b"
func (c Color) String() string {
switch c {
case White:
return "w"
case Black:
return "b"
default:
panic(fmt.Sprintf("Invalid color %d", c))
}
}
// Color direction factor
var moveDirectionFactor = [2]int{1, -1}
// Direction returns positive 1 for White and negative 1 (-1) for Black
func (c Color) Direction() int {
return moveDirectionFactor[c]
}
// Color pawn move direction
var pawnDir = [2]Direction{North, South}
// MoveDirection returns the direction of a pawn move for the color
func (c Color) MoveDirection() Direction {
return pawnDir[c]
}
var promRankBb = [2]Bitboard{Rank8_Bb, Rank1_Bb}
// PromotionRankBb returns the rank on which the given color promotes
func (c Color) PromotionRankBb() Bitboard {
return promRankBb[c]
}
var pawnDoubleRankBb = [2]Bitboard{Rank3_Bb, Rank6_Bb}
// PawnDoubleRank returns the rank from which the given color
// might make a second pawn push to achieve a pawn double move
func (c Color) PawnDoubleRank() Bitboard {
return pawnDoubleRankBb[c]
}